Effect of polymer entanglement on the toughening of double network hydrogels
Effect of polymer entanglement on the toughening of double network hydrogels
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DOI：
10.1021/jp052419n
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发表时间：
2005-09-01
影响因子：
3.3
通讯作者：
Gong, JP
中科院分区：
文献类型：
--
作者：
Tsukeshiba, H;Huang, M;Gong, JP
研究了以高交联聚（2-丙烯酰胺基-2-甲基丙磺酸）（PAMPS）为第一组分，线性聚丙烯酰胺（PAAm）为第二组分的双网络（DN）凝胶的力学强度。实验结果表明：（1）M-w是DN凝胶增韧的主要参数之一;（2）M-w = 10（6）是DN凝胶增韧的临界值;（3）M-w大于101的DN凝胶的断裂能高达10（3）J/m（2）。通过绘制DN凝胶的强度（断裂应力σ和断裂能G）对c[eta]的特征参数。其中c是DN凝胶中PAAm的平均浓度，[eta]是PAAm的特性粘度。发现DN凝胶的机械强度的显著增加发生在线性PAAm链彼此缠结的区域之上。因此，我们认为第二组分PAAm之间的缠结在DN凝胶的增韧机制中起着重要作用。该结果支持了非均相模型，该模型预测了第一网络PAMPS的“空隙”的存在，其尺寸远大于第二聚合物PAAm的半径。
The mechanical strength of double network (DN) gels consisting of highly cross-linked poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) as the first component and linear polyacrylamide (PAAm) as the second component has been investigated by varying the molecular weight of the second polymer PAAm, M-w. The experimental results reveal that, for toughening of the DN gels, (1) M-w is one of the dominant parameters, (2) there is a critical value of M-w = 10(6) for a remarkable enhancement: (3) the fracture energy of DN gels with a M-w, larger than 101 reaches a value as high as 10(3) J/m(2). By plotting the strength of DN gels (fracture stress sigma and fracture energy G) against a characteristic parameter of c[eta]. where c is the average concentration of PAAm in the DN gels and [eta] is the intrinsic viscosity of PAAm. it is found that the dramatic increase in the mechanical strength of the DN gels occurs above the region where linear PAAm chains are entangled with each other. Thus, we conclude that the entanglement between the second component PAAm plays an important role of the toughening mechanism of DN gels. This result supports the heterogeneous model, which predicts the presence of "voids" of the first network PAMPS with a size much larger than the radius of the second polymer PAAm.